Three separate genetic studies have reached the same conclusion: A specific gene mutation may account for up to half of all cases of age-related macular degeneration (AMD).

Many genes are known to be involved in AMD, and environmental factors add to the risk, but these studies mark a major milestone in understanding the disease.

In one study, researchers analyzed genetic data from more than 200 patients who were at high risk for developing AMD or who already had AMD in one or both eyes.1 They also analyzed more than 130 healthy participants who had no known family history of the disease. A variant (or polymorphism) of the complement factor H (CFH) gene was present in half of those with AMD or at high risk for the disease. In another study, researchers attributed 43% of AMD cases to the CFH mutation.2

The third study, which also identified the gene mutation, found that patients with two copies of the gene variant had more than a sevenfold risk for AMD.3

These studies may add to mounting evidence of the connection between AMD and inflammation. Previous studies indicated that CFH might play a role in protecting blood vessels from inflammation and damage. The genetic mutation likely offers less protection against inflammation.

This finding may lead to new methods to identify those at high risk, as well as point to possible drugs, one of the researchers says.

1. Edwards AO, Ritter Iii R, Abel KJ, et al. Complement factor H polymorphism and age-related macular degeneration. Science 2005 Mar 10; [Epub ahead of print].
2. Haines JL, Hauser MA, Schmidt S, et al. Complement factor H variant increases the risk of age-related macular degeneration. Science 2005 Mar 10; [Epub ahead of print].
3. Klein RJ, Zeiss C, Chew EY, et al. Complement factor H polymorphism in age-related macular degeneration. Science 2005 Mar 10; [Epub ahead of print].

Holy Guacamole! Avocados an Answer to AMD?


Break out the salsa and guacamole! Nutritionists have found that avocados boost absorption of luteinwhich may help protect against age-related macular degenerationas well as alpha-carotene and beta-carotene when eaten with other foods. Avocados are rich in dietary lipids, which are likely to be an important factor in carotenoid availability. Yet most fruits and veggies that are high in carotenoids are also low in lipids. The lipids in avocados, when added to salads and salsa, can significantly enhance the carotenoid absorption that occurs when those foods are eaten. 

Unlu NZ, Bohn T, Clinton SK, Schwartz SJ. Carotenoid absorption from salad and salsa by humans is enhanced by the addition of avocado or avocado oil. J Nutr 2005 Mar;135(3):431-6.



In Other AMD News:

Avastin improves vision after one week of treatment. Researchers at Miamis Bascom Palmer Eye Institute released results on the anti-VEGF (vascular endothelial growth factor) drug, Avastin (bevacizumab, Genentech). The first nine wet AMD patients treated with the drug (not yet FDA approved for AMD) showed an average improvement of two lines of vision in the study eye and three-lines in the fellow eye at three months. However, vision improvements were observed within one week of treatment. One difference between this and other ophthalmic anti-VEGF drugs: Avastin is a systemic intravenous treatment, not an intravitreal injection.

Photrex phase III trial gets underway. At the request of the FDA, Miravant Medical Technologies is planning a phase III confirmatory clinical trial on its Photrex treatment for wet AMD. Photrex (rostaporfin, formerly known as SnET2) previously received an approval letter from the FDA. The drug is used with PhotoPoint photodynamic therapy to selectively destroy abnormal blood vessels and stabilize vision loss.

Rheopheresis studies for dry AMD get the go-ahead. OccuLogix recently completed enrollment of 185 patients for a phase III clinical trial of its Rheo System to treat dry AMD. The FDA has given the company the OK to initiate crossover studies based on the previous trial. The aim of rheopheresis: to improve microvascular circulation in the eye by filtering high molecular weight proteins and other macromolecules from a patients plasma through a treatment process.

Vol. No: 142:4Issue: 4/15/05